Recovery of unsaturated oil from used hf catalyst



Dec. 11, 1951 RECOVERY OF UNSATURTED OIL FROM USED HF CA'FALYST J. P. O'NElL Filed Deo. 3l, 1948 Patented Dec. 1l, 1951 1 Claim.

This invention relates to the production of a high-boiling unsaturated oil from contaminants which are present in a liquid hydroiluoric acid catalyst which has been used in the conversion oi' organic compounds.

Concentrated hydronuoric acid. comprising essentially hydrogen iluoride, is commonly used as a catalyst for numerous reactions of organic compounds. Generally, such catalysts are used in the form of a liquid which, in its initial state, contains only hydrogen fluoride, except as commercially available materials always contain very small amounts of contaminants, such as water, sulfur dioxide, and the like. Such a catalyst is quite active in the conversion of various organic materials. Thus, it will enect reaction of paraiiln hydrocarbons by alkylation, isomerization, disproportionation', and the like. In alkylation, the paraffin hydrocarbon reacts with an alkylating reactant such as an olefin. an alkyl halide, an alcohol, or other reactive alkyl comcompounds and other non-hydrocarbon organic y impurities from liquid hydrocarbon materials, such as gasolines, kerosenes, lubricating oil fractions, and the like.

In all such uses, the hydrogen iluoride catalyst tends to become contaminated with catalyst soluble" carbonaceous materials formed by undesired side reactions, the accumulation of which in the composition results in gradual deactivation. Usually it is advantageous to renew and/or to regenerate the catalyst before the total accumulated catalyst-soluble material reaches about per cent by weight of the catalyst. If the proportion of catalyst-soluble materials becomes higher than this, the catalyst becomes ineilicient and the rate of formation of additional catalyst-soluble materials becomes excessively high.

In the regeneration of such a used hydroiluoric acid catalyst, it is frequently customary to subject at least a portion of it toA a treatment comprising removal of free hydrogen. iluoride from higher-boiling impurities by distillationv and recovery oi' hydrogen fluoride from organic iluorine materials present in such high-boiling impurities. This later part of the treatment includes heating an organic residue to decompose such compounds. forming additional free hydrogen iluoride. However. the resulting high-boillorganic iluorine compounds.

RECOVERY OF UNSATURATED OIL FROM USED HF CATALYST f .lolut P. oNeii, n, city, rex., mimorto Plump Petroleum Company, a corporation ot Delaware Application December 31, 1948, Serial No. 68,474

' ZBO-886 ing residue frequently still contains an appreciable amount of iluorine compounds, in part possibly some free hydrogen fluoride and in part amount of residual iiuorine is usually less than one per cent of this residual oil, and often is in' the range of 0.1 to 0.001 per cent. by weight of.

such oil, even this small amount is frequently undesirably large. as when this oil is to be used commercially.

I have now found that such a small residual amount oi' iluorine in the heavy organic oil recovered from such a used hydroiiuoric acid catalyst can be easily and successfully removed by contacting the oil, while it is liquid and prefer- \ably at the temperature at which it is available from the catalyst regeneration treatment just discussed, to the action oi' a bed of sand, or other siliceous material, under a subatmospheric pressure. In this latter treatment the iluorine, whether it be in the formo! hydrogen iluoride or of more resistant organic iluorine compounds, reacts with silicon compounds to form silicon tetrailuoride which is immediately removed from the reaction zone as a gas. and a iiuorine-free unsaturated liquid oil is separately removed from the reaction zone as a final product. While my invention is usually practiced in connection with the use of hydroiluoric acid alone as a catalyst, it may also be used to advantage when a small amount, such as 0.1 to 10 per cent by weight, of a promoter, such as boron triuoride, is included in the hydrofiuoric acid catalyst.-

An object of my invention is to produce a fluorine-free oil from a hydrofiuoric acid catalyst used in organic reactions.

A further object of my invention is to recover a valuable, highly unsaturated hydrocarbon oil as a by-product from a process for treating a hydrocarbon material with concentrated hydroiiuoric acid.

Further objects and advantages of my invention will become apparent, to one skilled in the art, from the accompanying disclosure and discussion.

My invention can be more clearly discussed. and various modifications of it disclosed, by a discussion of the accompanying drawing. This drawing is a schematic flow diagram of one arrangement of apparatus suitable for practicing my invention.

Referring now to the drawing, an organic reactant is introduced through line l0 into-reactor Il. wherein it is intimately mixed with a catalyst comprising concentrated hydroiluoric acid Although the total 3 introduced through line Il. Such an organic reactant may comprise a single material such as normal butane, or a polyalkyl aromatic hydroearbonwhenitis desiredtoisomerize suchamaterial, or it may comprise a mixture of reactants,

` such as an alkylatable organic compound to be alkylated and an alkylating reactant, such as discussed, or it may comprise a mixture of parafiin hydrocarbons to be subjected to disproportionation. or the like.

After a suitable reaction time, the mixture from reactor Il is passed through line Il to separator Il wherein it is separated into two liquid phases. as by cooling, and/or gravitational or centrifugal means. The phase rich in reactants and reaction products is generally the lighter phase and is passed through line il to separating means Il, which may comprise any necessary number of individual fractionating columns, and required auxiliary equipment, wherein organic eiliuents of reactor I I are separated into several desired products. by-products and recycled fractions. For example, low-boiling materials may be discharged through line it. Unreacted reactants can be recycled through line 2l to reactor il. A low-boiling product of the reaction can be recovered through line I1. High boiling products of the reaction can be recovered through line il. Any hydrogen fluoride which is present in the material passed through line Il to separating means II is recovered, and may be recycled to reactor ll through lines 2| and 25.

The heavier or catalyst phase from separator Il is in part recycled to reactor Il through line 2l and in partis passed for regeneration through line 2l to suitable regeneration means, illustrated by fractionators 21 and I3, which are equipped with suitable heating means 2l and 20A. respectively. and suitable cooling means 2l and 29A, respectively. In fractionator 21 the used hydroiluoric acid catalyst is distilled at a relatively low temperature, such as a kettle temperature between 100 and 150 F., to remove the large amount of free hydrogen fluoride present in the used catalyst. Resulting free hydrogen fluoride is removed as a low-boiling fraction through line il, and may be recycled to reactor H through lines Il and 2l or, if desired, may in part be discharged from the system. A high-boiling fraction comprising organic contaminants, together with a small amount of water, is removed through line I2 and passed to fractionator Il where it is subjected to distillation at a higher temperature, not only to remove water, but also to decompose organic fluorine compounds to form an unsaturated high-boiling oil and free hydrogen fluoride. Free hydrogen fluoride and water is removed as a lowbolling product through line 34 and may be recycled, at least in part, to reactor II through lines 3l, 3l and 25. Fractionator 3l is usually operated at a slight superatmospheric pressure, such as up to about 20 pounds per sq. inch guage, with a kettle temperature sufficiently high to decompose most of the organic fluorine compounds present in the material charged through line I2, such as between 200 and 350 F. The kettle product, which is usually a highly unsaturated organic oil with a fluorine content less than about l per cent by weight, and frequently between about 0.1 and 0.001 per cent by weight, is passed directly from the kettle of fractionator Il through line Il to the lower part of a bed Il of granular siliceous material. such as sand. in a reaction sone Il. It is unnecessary to heat this material above 4 i comes from the kettle of fractionator Il. so that it is introduced into reaction sone Il at a temperature of at least 200 F., and not higher than the kettle temperature in fractionator Il. While it is preferred that the siliceous material l in reactionsonellbeabedofgranularsilica,such as coarse sand or quartz, it may be some highly siliceous granular material such as a siliceous clay, Reaction sone Il is so constructed that there is a liquid .product withdrawal line u at a point above. the top of bed Il. but below a liquid level which is maintained within reaction sone Il by suitable means such as a weir. Above the liquid level is a vapor space and gaseous products are promptly withdrawn from the vapor space through line ll by vacuum pump l2. This vacuum pump maintains an absolute pressure whichis subatmospheric, and preferably between l0 and 500 mm. of mercury pressure absolute, in reaction sone Il. By these means silicon tetrailuoride is immediatelyremovedasagasassoonasitisformedby reaction of the siliceous material l0 with the iluorine compounds present in the hot residual liquid passed from the kettle of fractionator Il through line Il, and a fluorine-free unsaturated heavy oil is separately removed through line 4I. In order to accomplish this and produce a satisfactory fiuorine-free oil, such as one having a fluorine content below 0.0001 per cent by weight, I prefer to use a flow rate of oil through line Il between l and 5 liquid volumes per volume of siliceous material 4l per hour. When it is necessary to drain reaction zone Il, this may be accomplished by removing material through line Il. In the event it is necessary to remove material directly from the kettle of fractionator Il, this may be accomplished through line M. The unsaturated organic oil recovered as a product through line 48 is essentially a hydrocarbon oil when the reactants charged to reactor I I are hydrocarbons. alcohols, or hydrocarbon iiuorides. It usually has an initial boiling point of about 200-250 F., a bromine number between 20 and 100, a dark red or brownish color, a fiuorine content less than 0.0001 per cent by weight, and a specific gravity greater than 0.85.

It will be readily appreciated by one skilled in the art that the drawing is schematic only and that numerous pieces of additional equipment, such as contactors, means for removing the heat from such contactors, fractional distillation columns and associated equipment for separating means, and various pumps, flow control valves,

vheating and cooling means, and the like, have not been shown in detail. However, a sufllcient amount of the essential equipment and a discussion of the general flow, material compositions, and operating conditions have been given herein to act as a complete guide to one skilled in the art to enable him to adapt the invention and install equipment for any specific modification thereof.

As will be evident to those skilled in the art, various modifications of this invention can be made, or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claim.

I claim:

An improved process for producing a heavy, unsaturated oil from emuents of a process for reacting hydrocarbons in the presence of a liquid hydrofluoric acid catalyst, which comprises separating from enluents of such a process a liquid the temperature at which it is available when it hydmnuoc acid phase, subjecting gt least a porf/tion of said hvdrouoric acid phase to distillation to remove free hydrogen uoride from residual organic contaminants, subjecting said residual ated with a minor amount of more resistant organic uorne compounds, separating said contaminated liquid oil containing fluorine as an impurity in an amount between 1 and 0.001 per cent by weight from freed hydrogen uoride at said decomposition temperature and passing said oil as a liquid up through a bed of granular silica at a temperature between 200 and 350 F. under an absolute pressure between 10 and 500 mm. oi mercury at a flow rate between 1 and 5 volumes of said oil per volume of said granular silica per hour, withdrawing resulting silicon tetrauoride vapors from the top of said bed, and separately withdrawing a purified liquid oil from the top o! JOHN P. O'NEIL.

REFERENCES CITED The following references are of record in the 5 Said bed.

o le oi' this patent:

UNITED STATES PATENTS Number Name Date 2,377,546 Frey June 5, 1945 l5 2,388,918 Iverson Nov. 13, 1945 2,436,695 Kuhn Feb. 24,1948 2,463,930 Wildman Mar. 8. 1949 

